A substrate processing system includes a plurality of processing chambers, takes out a semiconductor wafer (hereinafter, simply referred to as a “wafer”) from a container such as, for example, a multi-application carrier (MAC) accommodating a plurality of wafers having a diameter of, for example, 450 mm, carries the wafer taken out from the container into each processing chamber, and performs various processings on the wafer in the processing chamber.
The wafer is taken out from the MAC by a transportation arm which can enter into the MAC. However, in order to deliver the wafer to the transportation arm smoothly, it is required to confirm a position of each wafer in the MAC (hereinafter, referred to as a “delivery position”) in advance.
A mapping arm is used to confirm a position of each wafer in the MAC. As illustrated in FIG. 9, a mapping arm 90 is provided with an expandable/retractable arm portion 91 and an optical sensor 92 installed at the tip of the arm portion 91. The mapping arm 90 is installed in a base 93 which can rotate and move up and down in opposition to a MAC 94 which is opened by removing a cover.
When confirming the position of each of the wafers W, the mapping arm 90 moves up/down and expands/retracts the arm portion 91 such that the sensor 92 is allowed to face each periphery of the wafers W, and confirms the position of the periphery as a position of the wafer W by the sensor 92. See, e.g., FIGS. 3 and 4 of Japanese Patent Laid-Open No. 2000-127069.
Further, an expandable/retractable transportation arm 95 is installed in the base 93. The transportation arm 95 enters into the MAC 94 on the basis of the confirmed position of the periphery of the wafer W, loads a portion near the center of the wafer W on a bifurcated plate-shaped end effector 96 installed at the tip, and then retreats from the inside of the MAC 94.